1. Field of the Invention
The present invention generally relates to a method, apparatus and system for detecting the mode and the guard interval, and more particularly to a method, apparatus and system for detecting the mode/guard interval for an orthogonal frequency division multiplexing (OFDM) system.
2. Description of the Prior Art
Orthogonal frequency division multiplexing (OFDM) is a communication technique that uses frequency division and multi-carrier modulation, and is widely applied in a variety of digital communication systems, such as the Digital Video Broadcasting (DVB), a standard drafted by Joint Technical Committee consisted of European Broadcasting Union, Comité Européen de Normalisation ELECtrotechnique, and European Telecommunications Standards Institute. In an OFDM system, there exist several modes according to respective Fast Fourier Transform (FFT) size. Further, a guard interval (GI) is inserted between adjacent data symbols for preventing inter-symbol interference. For minimizing the inefficiency owing to the guard interval insertion, a transmitter usually dynamically varies the length of the guard interval according to the quality of communication. Some transmitter sends pilot symbol to inform the receiver of the length of the guard interval, thereby complicating the system and lower down the process speed. Some OFDM systems without sending pilot signaling therefore need other ways to acquire the mode and the guard interval.
A few OFDM systems are conventionally proposed to overcome the drawbacks discussed above. Among the conventional OFDM systems, some cannot fully detect the mode/guard interval, while some detect the mode/guard interval with considerable error rate. For the reason, those conventional systems could not effectively overcome the drawbacks, a need has accordingly arisen to propose a method and system that could fully and automatically detect the mode/guard interval with insignificant error rate.